Opponents of genetically-modified food stepped up their campaign to declare Wales GM-free by staging a protest rally in Cardiff.

The event outside the Assembly building, Cardiff Bay, was organised by four pressure groups who say that even if some GM planting is allowed in Wales, conventional farmers should be protected.

They should receive compensation if neighbouring farms were found to have breached rules on cross-contamination, said campaigners.

Julian Rosser, director of Friends of the Earth Cymru (FoE Cymru), said there was no evidence that GM crops are safe for human health and the environment.

He said: "Even so, there is a risk that GM crops will be planted in Wales.

"It is vital the Assembly puts in place tough regulations to protect our environment and to preserve our right to choose GM-free food."

As well as FoE Cymru, other groups represented at yesterday's rally included GM Free Cymru, the Farmers' Union of Wales (FUW) and the National Federation of Womens Institutes Wales (NFWIW).

They met a selection of AMs from all political parties who agreed to call for the reconvening of a cross-party GM group within the Assembly to debate GM issues.

The EU has handed responsibility for deciding GM coexistence and crop separation distances to the UK government, which in principle supports GM crops in Britain. It is now deciding what legislation is needed: public consultations are expected this year.

FUW president Gareth Vaughan said Wales should remain focused on preventing any GM cultivation.

But if, as seems likely, some GM crops were allowed, legislation governing coexistence should be as tough as possible, with any additional costs met by the GM industry, he said.

Organic farmers should have "meaningful protection" and liability laws should be put in place to ensure biotech companies pay for contamination damages, he added.

Rhian Connick, head of the NFWIW, agreed: "Cross pollination seems inevitable, meaning if GM crops were to be grown in Wales, it would almost certainly mean an end to consumer choice, and irreversible damage to our countryside. The WI hopes the Assembly will set strict laws to prevent GM contamination and that those responsible for contamination are made to pay."

In a parallel GM rally staged by GM-free Britain at Westminster, London, former UK environment minister Michael Meacher said everyone except the government was against GM.

He said: "The only bodies in favour are the government, which is basically Tony Blair and Margaret Beckett."